1. Field of the Invention
The invention relates to fastening devices and refers more specifically to structure for and a method of fastening a member to other material by means of a compression member positioned adjacent one surface of the member having an opening at the surface of the member and fastening means inserted in the opening in the compression member engaging the surface of the member under compression.
2. Description of the Prior Art
In the past, when joining a member such as an aluminum extrusion to other material such as another aluminum extrusion, for example, screw runners have often been provided extruded simultaneously with one of the extrusions, whereby fastening of the two extrusions together has been accomplished by screws extending transversely through the other of the extrusions positioned perpendicularly to the one extrusion having the screw runners therein and into the screw runners of the one extrusion.
Typically, screw runners provide problems for extruders, since the throat, that is, the longitudinally extending opening of the screw runners have to be relatively narrow to contain a screw. This means that an extrusion die is weakened in the area of the screw runners. Usually, dies with screw runners in them are destroyed and have to be replaced long before they are worn out because a screw runner tab breaks out. Extrusion die life would on the average be more than doubled if screw runners could be eliminated.
One possible means of extending such die life may be to straighten out the generally arcuate legs of screw runners and subsequently to swedge them over in a fabricating operation at the ends of an extrusion only so that the screw runner takes a containment profile only at the end of the extrusion where screws are actually used. There are disadvantages to this approach in that an extra fabricating operation is required at each end of an extrusion and the screw runner still does not present an ideal situation in that the throat of the screw runner has been increased which initially appears to improve the die life but at the same time the length of the legs have been increased, which tends to reduce die life. The increased leg length tends to offset the advantage of a wider screw runner throat.
Another disadvantage to the typical screw runner utilizes in the past is that many times when a screw runner in a die starts to wear, or when there is any deviation in an extrusion which tends to make the inside diameter of the screw runner undersized or to slightly open the throat, or to mislocate the screw runner slightly, then in the assembly process a screw tends to be led out of the screw runner as it first enters the screw runner. The result of such wear and subsequent fabrication is a weak and ineffective joint which a fabricator never knows about until a produce fails after it is installed, since most such fastenings in fabrication are blind.
Also, some assemblies cannot use screw runners for fastening members to other material effectively because of the material used such as steel or because of other constraints such as wall thickness. For these and other applications, concealed fasteners might be desirable but have in the past sometimes been considered impossible on economic or efficiency grounds. Such assemblies have sometimes been fastened together with high strength brackets separately secured to each member to be joined.